This invention relates to a disc brake caliper support structure for use in rolling stock or railway cars.
In rolling stock, one known arrangement is to use a disc brake applied to disc rotors fixed to both sides of a wheel as shown in FIG. 1, wherein there is shown an arrangement of a track surface 21; a wheel flange 22; disc rotors 24, 24' fixed to both sides of the wheel 23; and a disc brake caliper 1 having pairs of friction pads 6, 6' in such a manner as to embrace the wheel 22 and to face the frictional surfaces of the disc rotors 24, 24', the caliper 1 being movably supported by a support member 2 fixed to the bogie frame through an upper guide pin 3 and a lower guide pin 4; a pair of cylinders 5 formed on the rear caliper arm; and a pair of anchor pins 7 fixed to the rear caliper arm. When hydraulic oil is supplied from an outside hydraulic source (not shown) to each cylinder 5, the piston in each cylinder 5 is moved and one of the friction pads 6 mate with one of the disc rotors 24 since a back plate of the friction pads 6 is supported, guided and pushed forward by each anchor pin 7. The caliper 1 is then moved rearwardly by the reactive force of the hydraulic pressure, causing the other friction pads 6' fixed to the front arm to made with the other disc rotor 24' fixed to the opposite side of the wheel, thereby braking the wheel.
The support member 2 integrally fixed to the bogie and the disc rotors 24, 24' each fixed to the wheel are caused to move independently of each other, since a spring or suspension means for isolating or reducing vibrations is interposed between the wheel and the bogie frame of the railway vehicle. To further stabilize a braking effect and to prevent the disc rotors 24, 24' from locally wearing, the disc brake caliper 1 for use in rolling stock should be movable in the axial direction of the upper and lower guide pins 3 and 4 relative to the support member 2, whereas the direction in which the upper and lower guide pins 3 and 4 should conform with the axis of rotation of the disc rotors 24 and 24'. Referring to FIGS. 2 and 3, a caliper support structure used in a conventional disc brake for the rolling stock will be described.
FIG. 2 shows a caliper support structure with the upper guide pin 3, wherein the caliper support comprises an upper lug la on the rear arm side of the caliper 1, an upper lug 1b on the front arm side thereof and an upper cylindrical portion 2a of the support member 2. An annular step 2a' is provided on the inner peripheral face of the upper cylindrical portion 2a. The outer peripheral face of a single split spherical bush 8 with a spherical member 9 having a through hole 9a is fitted over the inner peripheral face of the upper cylindrical portion. One side of the spherical bush 8 is made to abut against the annular side of the annular step 2a', the other being caught by a snap ring 10, and the spherical bush 8 is set in position relative to the upper cylindrical portion 2a. The upper guide pin 3 with one end having a large diameter portion 3a and the other end having a screw means 3b is passed through the upper lug 1b on the above-mentioned front arm side, the through hole 9a of the spherical member 9 and the upper lug 1a on the rear side. The upper guide pin 3 thus passed therethrough is also tightened with a nut 3c to make the caliper 1 slidable relative to the spherical member 9.
FIG. 3 shows a caliper support structure with the lower guide pin 4, wherein the caliper support comprises a lower lug 1a' on the rear arm side of the caliper 1, a lower lug 1b' on the front arm side thereof and a lower cylindrical portion 2b of the support member 2. The outer peripheral face of a centering rubber 11 having annular projections 11a formed inwardly toward both ends thereof is mated with the center of the inner peripheral face of the lower cylindrical portion 2b. Metal bushes 12, 13 are forced and fixed onto the inner peripheral face of the lower cylindrical portion 2b for use as both sides of the centering rubber 11.
The lower guide pin 4 having one end as a large diameter portion 4a and the other as a screw means 4b is passed through the lower lug 1b' on the front arm side, the through hole formed with the annular projection 11a of the centering rubber 11 and the lower lug 1a' on the rear arm side. The lower guide pin 4 is then tightened with a nut 4c to make the caliper 1 slidable relative to the centering rubber 11.
The caliper 1 is thus movably supported by the support member 2 and, in case the axial line of rotation of both the disc rotors 24, 24' is tilted, the upper guide pin 3 is allowed to swivel on the face where the spherical member 9 and the spherical bush 8 mate with each other to follow the tilt movement of the disc rotors 24, 24', whereas the lower guide pin 4 is also caused to follow while resiliently compressing and deforming the annular projection. In consequence, both the friction pads 6, 6' are forced to a uniformly abut against the disc rotors 24, 24'.
Numeral 17 designates a dust-proof rubber boot.
In the above conventional arrangement, however, the lower guide pin 4 is allowed to contact with the outer edges 12a, 13a of both bushes 12, 13 when the upper and lower guide pins 3, 4 are largely tilted. Consequently, the caliper 1 may become unable to move relative to the support member 2.